2 All these three kinds of will which we have mentioned belonged to the civil law, but later still a fourth form was introduced by the praetor's edict; for the new law of the praetor, or ius honorarium, dispensed with mancipation, and rested content with the seals of seven witnesses, whereas the seals of witnesses were not required by the civil law. 3 When, however, by a gradual process the civil and praetorian laws, partly by usage, partly by definite changes introduced by the constitution, came to be combined into a harmonious whole, it was enacted that a will should be valid which was wholly executed at one time and in the presence of seven witnesses (these two points being required, in a way, by the old civil law), to which the witnesses signed their names--a new formality imposed by imperial legislation--and affixed their seals, as had been required by the praetor's edict. Thus the present law of testament seems to be derived from three distinct sources; the witnesses, and the necessity of their all being present continuously through the execution of the will in order that the execution may be valid, coming from the civil law: the signing of the document by the testator and the witnesses being due to imperial constitutions, and the exact number of witnesses, and the sealing of the will by them, to the praetor's edict. 4 An additional requirement imposed by our constitution, in order to secure the genuineness of testaments and prevent forgery, is that the name of the heir shall be written by either the testator or the witnesses, and generally that everything shall be done according to the tenor of that enactment. 5 The witnesses may all seal the testament with the same seal; for, as Pomponius remarks, what if the device on all seven seals were the same? It is also lawful for a witness to use a seal belonging to another person. 6 Those persons only can be witnesses who are legally capable of witnessing a testament. Women, persons below the age of puberty, slaves, lunatics, persons dumb or deaf, and those who have been interdicted from the management of their property, or whom the law declares worthless and unfitted to perform this office, cannot witness a will. 7 In cases where one of the witnesses to a will was thought free at the time of its execution, but was afterwards discovered to be a slave, the Emperor Hadrian, in his rescript to Catonius Verus, and afterwards the Emperors Severus and Antoninus declared that of their goodness they would uphold such a will as validly made; for, at the time when it was sealed, this witness was admitted by all to be free, and, as such, had had his civil position called in question by no man. 8 A father and a son in his power, or two brothers who are both in the power of one father, can lawfully witness the same testament, for there can be no harm in several persons of the same family witnessing together the act of a man who is to them a stranger.